Abstract:The optimization problems of vibration control of long-span spatial structures are mainly studied.By studying and improving the classic ant colony optimization, this paper proposes the idea and the specific solution to introduce ant colony optimization into solving the optimal layout of dampers in long-span spatial structures, and the effectiveness is verified by the simulation results on typical reticulated shell structures.With the method of ant colony optimization applying on the spatial structures and effective calculation, the optimal layout of dampers which balance the effectiveness of vibration reduction and engineering economy can be obtained accurately.

Abstract:Taking the Changzhou Stadium-Kiewitt lamella ellipsoid parabolic shell as an example, two types of 6 kinds of hybrid ellipsoidal paraboloid reticulated shell parameterized design macro program are developed by using the APDL(Ansys Parametric Design Language)parameterized design language. ANSYS software is used to compare and analyze the force performance of 6 kinds of reticulated shells. The results show that:Under the same condition, the structure and mechanical properties of Kewitte-lamella ellipsoid parabolic shell is the most reasonable. Therefore, it's a priority selection in practical engineering. The vector span f/S of the first type hybrid elliptic paraboloid reticulated shell is 1/4~1/3 and the optimal force performance of second kinds of reticulated shells with sagittal span ratio f/S to 1/3~1/2 is optimal. This paper provides a certain reference for the shape optimization and engineering design of this kind of reticulated shell.

Abstract:In this paper, a numerical model of the vertical revetment sheet pile is established by using the finite element software ABAQUS, the effects of elastic modulus of the sheet pile, wave height and wavelength on the horizontal displacement of the pile body are studied.The results show that the vertical revetment sheet pile moves to the side of water, the displacement of the pile increases firstly and then decreases with the depth of pile increasing.The displacement is small below the depth of 13m. The elastic modulus of pile has little effect on the displacement of the pile.Under the same conditions, as the elastic modulus of pile increases, the horizontal displacement of pile from the pile top to a depth of 13m gradually decreases, the elastic modulus has little influence on the horizontal displacement of sheet pile below the depth of 13m.Wave height and wavelength have great influence on the horizontal displacement of the pile at the depth range from 0m to 13m, and they have little influence on the horizontal displacement of sheet pile below the depth of 13m.Under the same conditions, with increasing of wave height, the depth at the maximum displacement point of pile increases gradually, the horizontal displacement of the pile from the pile top to the depth of 13m decreases gradually.With increasing of wavelength, the horizontal displacement of the pile from pile top to the depth of 13m decreases gradually.

Abstract:Owing to inconformity of documents format of design model and construction model, there is a prominent question in the BIM implementation process of facade engineering from the design stage to the construction stage. The data needs to be re-processed and secondary processing during its transformation. To solve this problem, based on the comparative study of IFC standard and STEP standard, this paper establishes the partial mapping relation between them for the common types of curtain wall components, analyzes the similarities and differences in geometric expression, proposes the transformation algorithm of the geometric information of the curtain wall components from IFC format to STEP format, and implements the algorithm by using C++ language. Finally, the correctness and feasibility of the algorithm are verified by the actual case of the curtain wall components.

Abstract:Based on the IFC standard, this paper studies the real-time location algorithm of prefabricated components, utilizes IMU to record the location and attitude data of components in the process of installation and develops software and algorithm based on MEMS (Micro-Electro-Mechanical System) sensor. Combining the existing BIM component library, the automatic generation algorithm of building information model based on IFC standard is studied, and the final IFC data model is obtained by parameterization. it lays a foundation for automatic creation of as-built BIM of prefabricated buildings.

Abstract:In order to define the tensile behavior of reactive powder concrete-filled steel tube (RPCFST), the strain behavior and failure modes of RPC-FST were investigated by testing a total of 40 specimens under direct tension load with different curing temperatures, steel fiber volume contents and thicknesses of steel tube. It is shown from the test that, axial tension load-strain relationship of PRCFST is similar to that of concrete-filled steel tube (CFST); the cracking load is about 25 percent of peak load; the ultimate tensile resistant of RPC-FST can be specified by the method for CFST, which is simple and reliable, and can provide reference for engineering design.

Abstract:This paper is to study the influence of reservoir water level changes on the stability and deformation of steep slopes. Taking the left-bank slope of Jinping hydropower station as an example, based on the saturated seepage theories, the seepage is calculated under the changes of water level. In addition, the factor of safety of the slope is worked out with the Vector-Sum FoS Method during the seepage. New findings are as follows:when the reservoir water level has a rate of 1m/d from the elevation1880m to 800m, the safety factor of dam on the left bank of the head slip failure mode is reduced from 1.214 to 1.147, and the safety factor approaches a determined value as the water level tends to be stable. When the drawdown speed reaches 2m/d, the safety factor decreases more quickly; The maximum displacement of the slope is located at the shear outlet position of the potential sliding surface of the slip failure mode at the dam.

Abstract:Based on the investigation of the actual geological conditions of the project and the slope instability in the first stage of the project, this paper improves the accounting method of the original anti-slide pile reinforcement scheme, and finds out the inadequacies of the original reinforcement scheme of an artificial river in the lower reaches of the Yangtze River.Based on the actual situation of the weak layer in the slope soil layer, the reinforcement scheme of the cement mixing pile is presented.Through the calculation of reinforcement scheme with different replacement rates of 15%, 20% and 30%, we find the safety and stability of the slope of the reinforcement range.According to the calculation results of Geo-slope software, it can be found that the reinforcement scheme under different permutation rate can adjust the reinforcement range to make the safety and stability coefficient of the slope construction period meet the standard requirements.

Abstract:According to the existing investigation of seismic slope failure, tension cracks occur easily at the top of the slope which seriously affects the stability of the slope.However, the traditional stability analysis of seismic slope seldom considers tension cracks caused by soil fracture.In this paper, the equilibrium equation of force and moment is established based on the limit equilibrium-pseudo static method.The critical failure surface and its corresponding normal stress distribution are obtained by variational method.A closed form solution for the yield acceleration of seismic slope considering tension cracks is established without soil tensile strength.The study shows that tensile cracks will significantly reduce the stability of seismic slope and it reaches 50% for the vertical slope; The yield acceleration caused by the downward vertical seismic force is smaller when the slope inclination is bigger; In contrast, the upward vertical seismic force makes the yield acceleration smaller.

Abstract:In this paper, the motion of the soil under dynamic loads is analyzed by constructing a two-dimensional discrete element model, and the stress and strain at any time step are analyzed. The simulation is made by using two different shapes of particles which are the disk particles and the elliptical disc particles, directed against the simulation of single particle in the past.And these two kinds of particles have different Poisson's ratio and elastic modulus.Using Hertz contact theory, the contact between disc particles, between disc particles and elliptical disk particles and between disk particles or elliptic disk particles and the surrounding boundary are discussed in this paper.The normal stress and the particle overlap of the specific contact are deduced.Finally, by changing the mean value of different dynamic loads, the "backbone curve" is obtained, and the dynamic constitutive model of soil can be obtained by the nonlinear simulation of the "backbone curve".

Abstract:According to the small sample and nonlinear characteristics of the slope measurement data of foundation pit, a rolling prediction method of time series based on GA-LSSVM model for foundation pit wall measurement was presented.The cubic spline interpolation method was used to pretreat the time series of the foundation pit.Genetic algorithm (GA) was used to optimize the parameters in least squares support vector machine (LSSVM).The optimal parameter model was found out, and the GA-LSSVM time series rolling prediction model was established.The prediction results were evaluated by correlation coefficient R and the mean square error (Mean Squared Error, MSE).The method was applied to the prediction and analysis of the pit excavation of a subway station in Guangzhou, and it was compared with the least squares support vector machine (LSSVM) model without parameter optimization.The results showed that the correlation coefficient of the prediction model was high, the mean square error was small, the prediction result was more accurate.It is of great significance to improve the safety of the construction of the foundation pit and similar projects.

Abstract:To extend the discretized virtual internal bond (DVIB) to viscoelastic materials, a viscous bond is introduced into the original DVIB, paralleling to the original hyperelastic bond. Through the coupled hyperelastic and viscous bonds, the micro viscosity mechanism can be accounted. The preliminary researches on the numerical simulation of the rock viscoelasticity are conducted by this method. It suggests that this method can represent the typical three-stage-feature of creep, the elastic delay, rate-dependency of rock strength and creep fracturing process. The further simulation suggests that the viscosity has significant impact on the dynamic fracture initiation, propagation and branching. It delays the fracture growth and weakens the fracture branching. A new and feasible approach to viscoelasticity simulation is presented in this paper.

Abstract:With regard to the assumption of the effective consolidated stress method, the method was compared with the effective stress path method which is more rigorous in theory, and the calculated deviations of the effective consolidated stress method were analyzed.The Mohr stress circle of indoor isobaric and K0 consolidated undrained triaxial compression tests were considered.It is found that the result calculated by the effective consolidated stress method is accurate for the soil under isobaric consolidated state, while for the soil under K0 consolidated state, the deviations are related to the pore pressure parameter Af when soil mass is destroyed.If the values of Af are different, the calculation might be larger or smaller.For overconsolidated soft clay in practical engineering, the deviation is less than 15%.

Abstract:In order to study the strength property of graphene modified soil, the graphene is uniformly mixed in the soil for direct shear tests under the control of dry density, and the scanning electron microscopy(SEM) is used to observe the structure of shearing surface of soil samples.Graphene was put into soil samples with the dosage of 0%, 1%, 2%, 3% and 4%, the water contents are 14%, 16% and 18%.The results show that the graphene can improve the failure strength of the soil, and no optimum dosage is found in this test.The cohesion increases with the increase of the graphene dosage, and decreases with the increase of water content, but the internal friction angle is almost constant.With the help of SEM, the mechanism of the modification of graphene in soil is analyzed from the micro level. The incorporation of graphene can fill the soil pores and improve the friction between the soil particles, it can enhance the shear strength of the soil.

Abstract:The dry-wet cycling test, the free expansion rate test, unconfined compressive strength test are carried out for the expansive soil, lime improving expansive soil, the steel slag fine powder modified expansive soil to compare and verify the modified effect.The results show that the steel slag fine powder has improved significantly effect on the action of the expansive soil dry-wet circulation development of crack, the reduction of free expansion rate, the increase of strength.Among them, the modified effect of steel slag fine powder to free expansion rate is obviously behind the lime, but the ultimate improvement effect is similar.Strength improvement of steel slag fine powder is superior to lime. With the method of X-ray energy spectrum, the mineral composition and chemical composition of the expansive soil, lime improving expansive soil and the steel slag fine powder modified expansive soil are analyzed.The conclusion is that the mechanism of modifying expansive soil by steel slag fine powder is similar to the lime.

Abstract:In order to promote the engineering application of the recycled aggregate of construction waste, the natural aggregate was substituted by regenerated fine aggregate for the research parameters to configure four groups of recycled aggregate concrete.The cubic and prismatic compressive strength specimens were made.Based on the compressive strength tests for four groups of recycled aggregate concrete at different ages, the effect of the regenerated fine aggregate substitution ratio on the compressive properties of brick-rich recycled concrete was studied.The results show that the compressive strength of recycled concrete decreases under 28d age with the increase of the replacement rate of regenerated fine aggregate, but the effect is less at 3d and 7d.The calculation model between axial compressive strength and cuboidal compressive strength was obtained considering the influence of regenerated fine aggregate substitution rate.

Abstract:In order to study the shear resistance of brick-rich recycled concrete, four groups with different proportions of brick-rich recycled concrete specimens were prepared.Taking 28d cube compressive strength value as variable, the influence of cube compressive strength on shear stress-strain curve was studied based on the analysis of the effect of cubical compressive strength on shear strength. The results show that the shear failure mode of recycled brick-reinforced concrete is similar to that of ordinary concrete.With the increase of compressive strength, the shear strength of recycled brick-rich recycled concrete shows an obvious increasing trend.Based on the test results, the constitutive equation of shear stress-strain was established and the formula for calculating the shear modulus of brick-rich recycled concrete was proposed.

Abstract:In order to explore the vibration characteristics of multi storied buildings along the urban rail transit, a 4 story building beside the urban rail transit viaduct of a city is taken as the research object, and vibration tests are performed on each floor simultaneously.Then the vibration characteristics of each floor are analyzed by using linear weighting and Z weighting method, and the two weighting modes are analyzed respectively for the transmission characteristics of vibration under characteristic frequency. Finally, the finite element analysis software ABAQUS is used to establish the model and modal analysis is carried out and the cause of building vibration peak appearing on the 4th floor is found out.The results show that under the linear weighting and Z weighting, the global peak values of the 4 floors all appear in the 50~63Hz frequency range; during the propagation of vibration from the 1st floor to the 4th floor, the vibration acceleration levels of the center frequency of 50Hz and 63Hz frequency decreases at first and then increases and it reaches the minimum at the 2nd floor and reaches the maximum at the 4 floor.Modal analysis shows that when the train passes and when the frequency is 63Hz, the 4th floor resonance occurs, so the vibration is the most obvious.

Abstract:Because the existing method considers the loading control moment as a sum of the dead load on the bare beam before construction (mainly for bridge deck pavement) and the design vehicle load, the bearing capacity of the deck pavement is not considered, so the test result is not accurate.In this paper, a new method is proposed to determine the loading dominate moment of the bare beam static test.This method is based on the maximum strain with the combined effect of design vehicle loads and bridge deck pavement in the finished bridge state and the dominate moment is calculated reversely by the maximum strain through the second moment of area.This new approach has fully considered the construction and the process from the bare beam to the finished bridge state.The dead load of bridge deck pavement is borne entirely by the bare beam in the process of bridge construction, and a part of bridge deck pavement work with beam to form a stress whole to bear the design vehicle loads.The test results prove that the new method can achieve the precision of dominate moment and the refinement of test control in the bare beam static test.

Abstract:Based on the research and survey in Boyan, Boyan's physical defense is studied from three levels including the group layout, the organization and the detail structures of the traditional architecture.The study also discusses three material defensive psychology:the contrast between internal and external, feeling anxious under monitoring and self-suggestion.The study points out the defensive system of traditional architecture constitute with physical defense and material defensive.The defense characteristics is affected by Chinese traditional culture and business group culture, so it carries its regional features.The scientificity of the defensive system of traditional architecture is meaningful to the safety planning and designing for the contemporary architecture.

Abstract:Through the detailed analysis of the parasitic effect of ESD protection on the noise performance of low noise amplifier (LNA), a new noise optimization technique for LNA with ESD protection is proposed, and concrete design formulas are presented.The LNA designed by this optimization technique can approach to or equal to the minimum noise figure of a single transistor. Simulation is carried out under 0.25μm CMOS process, the results indicate that the designed LNA can approach to the minimum noise figure under different power consumptions, therefore the effectiveness of the proposed optimization technique is verified.The proposed optimization technique can be widely used in the design of the LNA.

Abstract:In the information security area, traditionally m-sequence is used as the base sequence on which non-linear combination, non-linear filtering and non-uniform sampling are applied to generate a sequence with high linear complexity. Yet the stability of linear complexity of such a sequence is not satisfactory. In this paper, we propose m-subsequence which is generated by changing the state transition order of the m-sequence. Since the m-subsequence is made by changed the order of the m -sequence, it is a non-linear sequence. The linear complexity is shown to be stable and exponential in the length of the shift register by testing data. In addition, the k-error linear complexity remains the same as the length of the shift register grows.

Abstract:Taking a landslide in Shaanxi as an example, the influence of relative position of mine caves that parallel to the strata and weak-soft zone on slope stability is studied by using the discontinuous deformation (DDA) theory.On the basis of the landslide' s characteristics, basic geological conditions and mechanical parameters, the landslide practical model for calculation and analysis is established.The analysis results show that the mine caves affect the distribution of slope stress field and different relative positions of mine caves and weak-soft zone have different effects on the slope stability.If the distance between mine caves and weak belt is 2-5 times longer than the height of mine cave, the stability of slope will be reduced.When the distance between mine caves and weak belt is 5-6 longer times than the height of mine cave, the slope is the most dangerous, and then relieves with increasing distance.When the distance between mine caves and weak belt is more than 8 times longer than the height of gob, slope will be safe.

Abstract:In this paper, a theoretical and simulated experimental study on the tight focusing properties of radial vector Gaussian beam loaded with symmetrical four vortex phases is presented. This is the process:loading a symmetrical four vortex phase in the radial vector optical field, adjusting the distance between the singularity of the vortex phase center and the optical field center, and then compact focusing based on the Vector diffraction theory proposed by Richards and Wolf. The results prove that, when the distance between the singularity of the vortex phase center and the optical field center is 0.62w, five focal spots can be obtained. And the energy distribution of the focal spot can be regulated by adjusting the distance between the vortex phase. This research can be applied to the area of ultra-fast laser micro machining, multi-particle trapping, optical tweezers and etc.